The present invention relates to an expandable seal arrangement. More particularly, the present invention relates to an expandable compression ring for exerting an outwardly, radially directed force on an inner surface of a gasket to compress said gasket into sealing arrangement with a wall of an opening.
Compressing rings may be used to clamp an exterior surface of a resilient gasket surrounding a pipe into an opening in which the pipe is inserted. The gasket used is typically constructed of an elastomeric material and, when clamped into position, provides a fluid-tight seal between the pipe and the opening. Clamping is accomplished by expanding the compression ring against the interior surface of the gasket.
Several designs for clamping bands exist. For example, U.S. Pat. No. 5,054,794 to Westhoff et al. discloses an expansion ring formed from a C-shaped annular, metal band and a generally S-shaped spanning member. The C-shaped annular band has a circumference of less than 360.degree. such that a gap exists between first and second ends of the annular band. The annular band also has a generally U-shaped channel into which the spanning member is disposed. A first end of the spanning member is welded into the generally U-shaped channel of the annular band. A second end of the spanning member has a locking tongue formed thereon that engages a locking member welded in the U-shaped channel of the annular band. A guide member is also welded in the U-shaped channel of the annular band and holds the spanning member therein. At least two disadvantages exist with the design of Westhoff et al. The first is that the gap between the first and second ends of the annular band presents a discontinuity to the inner surface of the gasket in which it is disposed. During expansion of the ring of Westhoff et al., this circumferential discontinuity will result in a non-uniform pressure surface area being exerted on the inner surface of the gasket. Westhoff et al. also suffers from the disadvantage that it is formed from multiple pieces of metal that require numerous welding operations for assembly.
Another example is U.S. Pat. No. 4,478,437 which is assigned to the assignee of the present invention. This patent discloses a radially expandable locking sleeve preferably formed of a flat steel strip of substantially uniform thickness. The sleeve is formed in an annular shape and has interlocking end portions. The ends portions lock the sleeve into a single expanded position. The outer circumferential surface of the locking sleeve presents a substantially uninterrupted pressure surface to the gasket, including across the interlocking ends portions.
A further example is U.S. Pat. No. 5,150,927, also assigned to the assignee of the present invention. This patent discloses a sliding sleeve and a radially expandable compression sleeve. The sliding sleeve is positioned adjacent the portion of the inner surface of the gasket to be expanded. The compression sleeve is disposed immediately adjacent the sliding sleeve which serves as a slip plate during expansion of the compression sleeve. The sliding sleeve may be attached to or integrally molded into the inner surface of the tubular gasket. The compression sleeve may be a one-or two-piece assembly that is expandable into multiple locked positions. Locking is accomplished via engagement of radially inwardly and outwardly facing teeth. The inwardly facing teeth are received in well-shaped tooth receiving recesses.
Applicant makes no representation by this discussion, nor should any such representation be inferred, that an exhaustive search of all relevant prior art has been conducted, or that no more pertinent prior art exists.
The arrangements described in U.S. Pat. Nos. 4,478,437 and 5,150,927 work well for their intended purpose. Each has its own advantages and a design that incorporated these advantages as well as providing additional ones would be a welcome improvement. Accordingly, a compression ring for exerting an outwardly, radially directed force on an inner surface of a gasket to compress the gasket into sealing engagement with a wall of an opening is provided. The subject invention has an integrally molded one-piece body or strip of resiliently flexible material. The body or strip has a substantially continuous and uninterrupted exterior circumferential surface. This exterior surface exerts a generally uniform pressure on an inner surface of the gasket. The strip has first and second ends. The first end overlaps the second end when the strip or body is formed into a ring. Integrally molded means on the body or strip cooperate with force exerting means to move the body or strip into an expanded position. In addition, means integrally molded on the body or strip lock the same into the expanded position. In preferred embodiments, the ring is integrally formed from plastic. The first end of the body or strip and a portion adjacent thereto may taper to a feather edge so as to provide the substantially continuous and uninterrupted circumferential surface. The cooperating means may comprise one or more lugs on a surface of the body or strip, for example, the interior surface of the body or strip. The cooperating means may further comprise holding means on the second end of the body or strip. The holding means may be a recess formed in the second end.
The locking means may comprise integrally molded cooperating projections on separate portions of the strip or body. The projections may be teeth-like structures a set of which are on an interior portion of the body or strip and a set of which are on an exterior portion of the body or strip adjacent the second end thereof. The teeth on one portion of the body or strip may be angled in a first direction and the teeth on the other portion of the body or strip may be angled in a second direction opposite the first direction.
The ring may further comprise guide means for limiting lateral movement of the first and second ends of the body or strip relative to one another. The guide means may comprise at least two opposing tabs on an exterior surface of the body or strip.
The compression ring may further include anchoring means integrally molded on the body or strip for securing the same against lateral movement in the gasket. The anchoring means may circumferentially extend around at least a portion of an exterior surface of the body or strip. The anchoring means may be a generally continuous protrusion that extends substantially orthogonally from the exterior surface of the body or strip.
The ring may be formed so that the body or strip thereof is expandable into multiple locked positions.
In another embodiment of the present invention, the compression ring comprises integrally molded first and second portions made from resiliently flexible material. In preferred embodiments, the ring is integrally formed from plastic. Means integrally molded on the first portion for cooperating with the force exerting means for moving the body into an expanded position is also provided. In addition, means for locking the first and second portions together to form the ring so that exterior surfaces of the first and second portions form a substantially continuous and uninterrupted circumferential surface is also provided. The locking means is integrally molded on the first and second portions. The exterior surface of the compression ring exerts a generally uniform pressure on the inner surface of the gasket. The first and second ends of the second portion and portions adjacent thereto may taper to a feather edge so as to provide the substantially continuous and uninterrupted circumferential surface.
The cooperating means may comprise holding means on first and second ends of the first portion. The holding means may comprise lugs. Alternatively, the holding means may be recesses formed in the first and second ends.
The locking means may comprise integrally molded projections on an exterior surface of the first portion and an interior surface of the second portion. The projections may be teeth-like structure. Groups of the teeth of the first portion may be angled in a first direction and groups of the teeth of a second portion may be angled in a second direction opposite the first direction.
The compression ring may further comprise anchoring means for securing the ring against lateral movement in the gasket.
The ring may be formed so as to be expandable into multiple locked positions.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.